Ion exchange chromatography (IC) is an analytical technique used to separate charged molecules including ions, proteins, small nucleotides, and amino acids. It can function in anion or cation mode. In this dissertation, anion exchange chromatography was used, and column materials were made in our lab with resorcinarene-based compounds called cavitands. Cavitands create cavities to bind to molecules because of their three-dimensional structure. Two new gradient IC methods were established to identify and quantify perrhenate and perfluoroalkyl substances (PFAS) by customized resorcinarene-based column, zinc cyclen resoecinarene (ZCR) and arginine methyl ester (RUE) columns. The ZCR column accomplished outstanding separation of perrhenate from other anions such as chloride and sulfate by using a gradient elution of 2-60 mM NaOH. There was a logarithmic relationship between the perrhenate concentration and its retention time. In addition to separating anions, the ZCR column was able to preconcentrate perrhenate with over 90% recovery in different conditions. RUE was successfully synthesized and attached to polystyrene resin and used in IC to separate the PFAS, perfluorobutanoic acid (PFBA), perfluoropentanoic acid (PFPeA), perfluorobutanesulfonic acid (PFBS), perfluorohexanoic acid (PFHxA), perfluorohexanesulphonic acid (PFHxS), and perfluorooctanoic acid (PFOA). The sample preparation for the PFAS was simple and only needed filtration. A gradient method starting with 70 mM NaOH and going to pure water was necessary to separate the PFAS. There was no detectable PFAS in Provo tap water and Utah Lake water by our method. Although the LOD and LOQ of PFAS were not as low as the existing methods, the IC method does not require complicated sample preparation steps to separate and quantify PFAS. Binding studies of RUE and RUA were done with organic acids, including citric, malic, and succinic acid, and PFAS including PFBA, and PFHxA. The strongest binding was for L-malic acid followed by succinic acid, D-malic acid, pentanoic acid, citric acid, and dimethyl L-malate. RUE displayed some chiral recognition between L-malic acid and D-malic acid. Unfortunately, it did not show significant differences in binding between the different PFAS even though RUE had been able to separate them by IC.
| Identifer | oai:union.ndltd.org:BGMYU2/oai:scholarsarchive.byu.edu:etd-11074 |
| Date | 16 August 2023 |
| Creators | Chan, Wai Ning |
| Publisher | BYU ScholarsArchive |
| Source Sets | Brigham Young University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Theses and Dissertations |
| Rights | https://lib.byu.edu/about/copyright/ |
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